src/bin/lttng-sessiond/register.c

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  * Copyright (C) 2013 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-only
   7  *
   8  */
   9
  10 #include <stddef.h>
  11 #include <stdlib.h>
  12 #include <urcu.h>
  13 #include <common/futex.h>
  14 #include <common/macros.h>
  15 #include <common/shm.h>
  16 #include <common/utils.h>
  17 #include <sys/stat.h>
  18
  19 #include "register.h"
  20 #include "lttng-sessiond.h"
  21 #include "testpoint.h"
  22 #include "health-sessiond.h"
  23 #include "fd-limit.h"
  24 #include "utils.h"
  25 #include "thread.h"
  26
  27 struct thread_state {
  28         struct lttng_pipe *quit_pipe;
  29         struct ust_cmd_queue *ust_cmd_queue;
  30         sem_t ready;
  31         bool running;
  32         int application_socket;
  33 };
  34
  35 /*
  36  * Creates the application socket.
  37  */
  38 static int create_application_socket(void)
  39 {
  40         int ret = 0;
  41         int apps_sock;
  42         const mode_t old_umask = umask(0);
  43
  44         /* Create the application unix socket */
  45         apps_sock = lttcomm_create_unix_sock(
  46                         the_config.apps_unix_sock_path.value);
  47         if (apps_sock < 0) {
  48                 ERR("Create unix sock failed: %s",
  49                                 the_config.apps_unix_sock_path.value);
  50                 ret = -1;
  51                 goto end;
  52         }
  53
  54         /* Set the cloexec flag */
  55         ret = utils_set_fd_cloexec(apps_sock);
  56         if (ret < 0) {
  57                 ERR("Unable to set CLOEXEC flag to the app Unix socket (fd: %d). "
  58                                 "Continuing but note that the consumer daemon will have a "
  59                                 "reference to this socket on exec()", apps_sock);
  60         }
  61
  62         /* File permission MUST be 666 */
  63         ret = chmod(the_config.apps_unix_sock_path.value,
  64                         S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
  65                                         S_IWOTH);
  66         if (ret < 0) {
  67                 PERROR("Set file permissions failed on %s",
  68                                 the_config.apps_unix_sock_path.value);
  69                 goto error_close_socket;
  70         }
  71
  72         DBG3("Session daemon application socket created (fd = %d) ", apps_sock);
  73         ret = apps_sock;
  74 end:
  75         umask(old_umask);
  76         return ret;
  77 error_close_socket:
  78         if (close(apps_sock)) {
  79                 PERROR("Failed to close application socket in error path");
  80         }
  81         apps_sock = -1;
  82         ret = -1;
  83         goto end;
  84 }
  85
  86 /*
  87  * Notify UST applications using the shm mmap futex.
  88  */
  89 static int notify_ust_apps(int active, bool is_root)
  90 {
  91         char *wait_shm_mmap;
  92
  93         DBG("Notifying applications of session daemon state: %d", active);
  94
  95         /* See shm.c for this call implying mmap, shm and futex calls */
  96         wait_shm_mmap = shm_ust_get_mmap(
  97                         the_config.wait_shm_path.value, is_root);
  98         if (wait_shm_mmap == NULL) {
  99                 goto error;
 100         }
 101
 102         /* Wake waiting process */
 103         futex_wait_update((int32_t *) wait_shm_mmap, active);
 104
 105         /* Apps notified successfully */
 106         return 0;
 107
 108 error:
 109         return -1;
 110 }
 111
 112 static void cleanup_application_registration_thread(void *data)
 113 {
 114         struct thread_state *thread_state = data;
 115
 116         if (!data) {
 117                 return;
 118         }
 119
 120         lttng_pipe_destroy(thread_state->quit_pipe);
 121         free(thread_state);
 122 }
 123
 124 static void set_thread_status(struct thread_state *thread_state, bool running)
 125 {
 126         DBG("Marking application registration thread's state as %s", running ? "running" : "error");
 127         thread_state->running = running;
 128         sem_post(&thread_state->ready);
 129 }
 130
 131 static bool wait_thread_status(struct thread_state *thread_state)
 132 {
 133         DBG("Waiting for application registration thread to be ready");
 134         sem_wait(&thread_state->ready);
 135         if (thread_state->running) {
 136                 DBG("Application registration thread is ready");
 137         } else {
 138                 ERR("Initialization of application registration thread failed");
 139         }
 140
 141         return thread_state->running;
 142 }
 143
 144 static void thread_init_cleanup(void *data)
 145 {
 146         struct thread_state *thread_state = data;
 147
 148         set_thread_status(thread_state, false);
 149 }
 150
 151 /*
 152  * This thread manage application registration.
 153  */
 154 static void *thread_application_registration(void *data)
 155 {
 156         int sock = -1, i, ret, pollfd, err = -1;
 157         uint32_t revents, nb_fd;
 158         struct lttng_poll_event events;
 159         /*
 160          * Gets allocated in this thread, enqueued to a global queue, dequeued
 161          * and freed in the manage apps thread.
 162          */
 163         struct ust_command *ust_cmd = NULL;
 164         const bool is_root = (getuid() == 0);
 165         struct thread_state *thread_state = data;
 166         const int application_socket = thread_state->application_socket;
 167         const int quit_pipe_read_fd = lttng_pipe_get_readfd(
 168                         thread_state->quit_pipe);
 169
 170         DBG("[thread] Manage application registration started");
 171
 172         pthread_cleanup_push(thread_init_cleanup, thread_state);
 173         health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG);
 174
 175         ret = lttcomm_listen_unix_sock(application_socket);
 176         if (ret < 0) {
 177                 goto error_listen;
 178         }
 179
 180         /*
 181          * Pass 2 as size here for the thread quit pipe and apps_sock. Nothing
 182          * more will be added to this poll set.
 183          */
 184         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
 185         if (ret < 0) {
 186                 goto error_create_poll;
 187         }
 188
 189         /* Add the application registration socket */
 190         ret = lttng_poll_add(&events, application_socket, LPOLLIN | LPOLLRDHUP);
 191         if (ret < 0) {
 192                 goto error_poll_add;
 193         }
 194
 195         /* Add the application registration socket */
 196         ret = lttng_poll_add(&events, quit_pipe_read_fd, LPOLLIN | LPOLLRDHUP);
 197         if (ret < 0) {
 198                 goto error_poll_add;
 199         }
 200
 201         set_thread_status(thread_state, true);
 202         pthread_cleanup_pop(0);
 203
 204         if (testpoint(sessiond_thread_registration_apps)) {
 205                 goto error_poll_add;
 206         }
 207
 208         while (1) {
 209                 DBG("Accepting application registration");
 210
 211                 /* Inifinite blocking call, waiting for transmission */
 212         restart:
 213                 health_poll_entry();
 214                 ret = lttng_poll_wait(&events, -1);
 215                 health_poll_exit();
 216                 if (ret < 0) {
 217                         /*
 218                          * Restart interrupted system call.
 219                          */
 220                         if (errno == EINTR) {
 221                                 goto restart;
 222                         }
 223                         goto error;
 224                 }
 225
 226                 nb_fd = ret;
 227
 228                 for (i = 0; i < nb_fd; i++) {
 229                         health_code_update();
 230
 231                         /* Fetch once the poll data */
 232                         revents = LTTNG_POLL_GETEV(&events, i);
 233                         pollfd = LTTNG_POLL_GETFD(&events, i);
 234
 235                         /* Thread quit pipe has been closed. Killing thread. */
 236                         if (pollfd == quit_pipe_read_fd) {
 237                                 err = 0;
 238                                 goto exit;
 239                         } else {
 240                                 /* Event on the registration socket */
 241                                 if (revents & LPOLLIN) {
 242                                         sock = lttcomm_accept_unix_sock(application_socket);
 243                                         if (sock < 0) {
 244                                                 goto error;
 245                                         }
 246
 247                                         /*
 248                                          * Set socket timeout for both receiving and ending.
 249                                          * app_socket_timeout is in seconds, whereas
 250                                          * lttcomm_setsockopt_rcv_timeout and
 251                                          * lttcomm_setsockopt_snd_timeout expect msec as
 252                                          * parameter.
 253                                          */
 254                                         if (the_config.app_socket_timeout >= 0) {
 255                                                 (void) lttcomm_setsockopt_rcv_timeout(sock,
 256                                                                 the_config.app_socket_timeout * 1000);
 257                                                 (void) lttcomm_setsockopt_snd_timeout(sock,
 258                                                                 the_config.app_socket_timeout * 1000);
 259                                         }
 260
 261                                         /*
 262                                          * Set the CLOEXEC flag. Return code is useless because
 263                                          * either way, the show must go on.
 264                                          */
 265                                         (void) utils_set_fd_cloexec(sock);
 266
 267                                         /* Create UST registration command for enqueuing */
 268                                         ust_cmd = zmalloc(sizeof(struct ust_command));
 269                                         if (ust_cmd == NULL) {
 270                                                 PERROR("ust command zmalloc");
 271                                                 ret = close(sock);
 272                                                 if (ret) {
 273                                                         PERROR("close");
 274                                                 }
 275                                                 sock = -1;
 276                                                 goto error;
 277                                         }
 278
 279                                         /*
 280                                          * Using message-based transmissions to ensure we don't
 281                                          * have to deal with partially received messages.
 282                                          */
 283                                         ret = lttng_fd_get(LTTNG_FD_APPS, 1);
 284                                         if (ret < 0) {
 285                                                 ERR("Exhausted file descriptors allowed for applications.");
 286                                                 free(ust_cmd);
 287                                                 ret = close(sock);
 288                                                 if (ret) {
 289                                                         PERROR("close");
 290                                                 }
 291                                                 sock = -1;
 292                                                 continue;
 293                                         }
 294
 295                                         health_code_update();
 296                                         ret = ust_app_recv_registration(sock, &ust_cmd->reg_msg);
 297                                         if (ret < 0) {
 298                                                 free(ust_cmd);
 299                                                 /* Close socket of the application. */
 300                                                 ret = close(sock);
 301                                                 if (ret) {
 302                                                         PERROR("close");
 303                                                 }
 304                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 305                                                 sock = -1;
 306                                                 continue;
 307                                         }
 308                                         health_code_update();
 309
 310                                         ust_cmd->sock = sock;
 311                                         sock = -1;
 312
 313                                         DBG("UST registration received with pid:%d ppid:%d uid:%d"
 314                                                         " gid:%d sock:%d name:%s (version %d.%d)",
 315                                                         ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
 316                                                         ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
 317                                                         ust_cmd->sock, ust_cmd->reg_msg.name,
 318                                                         ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);
 319
 320                                         /*
 321                                          * Lock free enqueue the registration request. The red pill
 322                                          * has been taken! This apps will be part of the *system*.
 323                                          */
 324                                         cds_wfcq_enqueue(&thread_state->ust_cmd_queue->head,
 325                                                         &thread_state->ust_cmd_queue->tail,
 326                                                         &ust_cmd->node);
 327
 328                                         /*
 329                                          * Wake the registration queue futex. Implicit memory
 330                                          * barrier with the exchange in cds_wfcq_enqueue.
 331                                          */
 332                                         futex_nto1_wake(&thread_state->ust_cmd_queue->futex);
 333                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 334                                         ERR("Register apps socket poll error");
 335                                         goto error;
 336                                 } else {
 337                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 338                                         goto error;
 339                                 }
 340                         }
 341                 }
 342         }
 343
 344 exit:
 345 error:
 346         /* Notify that the registration thread is gone */
 347         notify_ust_apps(0, is_root);
 348
 349         ret = close(application_socket);
 350         if (ret) {
 351                 PERROR("Failed to close application registration socket");
 352         }
 353         if (sock >= 0) {
 354                 ret = close(sock);
 355                 if (ret) {
 356                         PERROR("Failed to close application socket");
 357                 }
 358                 lttng_fd_put(LTTNG_FD_APPS, 1);
 359         }
 360         unlink(the_config.apps_unix_sock_path.value);
 361
 362 error_poll_add:
 363         lttng_poll_clean(&events);
 364 error_listen:
 365 error_create_poll:
 366         DBG("UST Registration thread cleanup complete");
 367         if (err) {
 368                 health_error();
 369                 ERR("Health error occurred in %s", __func__);
 370         }
 371         health_unregister(the_health_sessiond);
 372         return NULL;
 373 }
 374
 375 static bool shutdown_application_registration_thread(void *data)
 376 {
 377         struct thread_state *thread_state = data;
 378         const int write_fd = lttng_pipe_get_writefd(thread_state->quit_pipe);
 379
 380         return notify_thread_pipe(write_fd) == 1;
 381 }
 382
 383 struct lttng_thread *launch_application_registration_thread(
 384                 struct ust_cmd_queue *cmd_queue)
 385 {
 386         int ret;
 387         struct lttng_pipe *quit_pipe;
 388         struct thread_state *thread_state = NULL;
 389         struct lttng_thread *thread = NULL;
 390         const bool is_root = (getuid() == 0);
 391         int application_socket = -1;
 392
 393         thread_state = zmalloc(sizeof(*thread_state));
 394         if (!thread_state) {
 395                 goto error_alloc;
 396         }
 397         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 398         if (!quit_pipe) {
 399                 goto error;
 400         }
 401         thread_state->quit_pipe = quit_pipe;
 402         thread_state->ust_cmd_queue = cmd_queue;
 403         application_socket = create_application_socket();
 404         if (application_socket < 0) {
 405                 goto error;
 406         }
 407         thread_state->application_socket = application_socket;
 408         sem_init(&thread_state->ready, 0, 0);
 409
 410         thread = lttng_thread_create("UST application registration",
 411                         thread_application_registration,
 412                         shutdown_application_registration_thread,
 413                         cleanup_application_registration_thread,
 414                         thread_state);
 415         if (!thread) {
 416                 goto error;
 417         }
 418         /*
 419          * The application registration thread now owns the application socket
 420          * and the global thread state. The thread state is used to wait for
 421          * the thread's status, but its ownership now belongs to the thread.
 422          */
 423         application_socket = -1;
 424         if (!wait_thread_status(thread_state)) {
 425                 thread_state = NULL;
 426                 goto error;
 427         }
 428
 429         /* Notify all applications to register. */
 430         ret = notify_ust_apps(1, is_root);
 431         if (ret < 0) {
 432                 ERR("Failed to notify applications or create the wait shared memory.\n"
 433                         "Execution continues but there might be problems for already\n"
 434                         "running applications that wishes to register.");
 435         }
 436
 437         return thread;
 438 error:
 439         lttng_thread_put(thread);
 440         cleanup_application_registration_thread(thread_state);
 441         if (application_socket >= 0) {
 442                 if (close(application_socket)) {
 443                         PERROR("Failed to close application registration socket");
 444                 }
 445         }
 446 error_alloc:
 447         return NULL;
 448 }